Lubricating compositions



United States Patent 3,174,932 LUBRICATENG COMkOSlTlONS Arnold J. Morway, Clark, N.J., assignor to Esso Research and Engineering (Iornpany, a corporation of Delaware No Drawing. Filed Jan. 9, 1961, Ser. No. 81,245 10 Claims. (Cl. 252-39) This invention relates to novel metallo-organic complex compounds and to compositions containing the same. More particularly, the present invention pertains to metal salt complexes of organic acids containing metal salts of low molecular Weight carboxylic acid not exceeding 102 molecular weight, and of moderate molecular weight carboxylic acid between 124 and 176 molecular weight, and to compositions containing the same. The term salt complex pertains to the product or products obtained by heating or reacting together the mixture of low and moderate molecular weight carboxylic acid salts at a tempera ture of at least about 400 F.

This application is a continuation-in-part of Serial Number 498,739, filed April 1, 1955, entitled Complex Metal Salt Compositions, and now abandoned.

In general, the invention relates to compositions containing complex compounds of at least one metal salt of a low molecular weight carboxylic acid, containing 1 to 3 carbon atoms per molecule and at least one metal salt of an intermediate molecular weight carboxylic acid, containing from about 7 to 10 carbon atoms, in which the mol ratio of low molecular weight carboxylic acid to intermediate molecular weight carboxylic acid is above about 2 to l and below about 40 to 1. The compositions of the invention include novel and improved greases, lubricating fluids, etc. In particular, grease compositions containing the complex materials of the invention have been found to have excellent extreme pressure characteristics in addition to other outstanding grease properties with respect to stability, penetration, dropping point, etc. The use of soap-salt complexes as grease thickeners is well known in the art. The complex materials used heretofore consisted of combinations of metal soaps of high molecular weight carboxylic acids and metal salts of low molecular Weight carboxylic acids containing from 1 to 5 carbon atoms. The commonly known grease-making, high molecular weight fatty acids, saturated or unsaturated, containing from 12 to 22 carbon atoms have been employed in conjunction with such low molecular weight carboxylic acids as acetic, propionic, alkoxy propionic, furoic and the like to form the complex grease thickeners of the prior art. Normally about equimolar proportions of low to high molecular weight carboxylic acids have been employed by the prior art, because of the low thickening efiect of the low molecular weight carboxylic acid constituent. Recently it has been noted that highly desirable characteristics can be obtained by making complexes with drastically increased content of the low molecular weight acid and consequently with increased metal content of the soap-salt complexes. These complexes contain at least 7 moles and up to 40 moles or more of the loW molecular weight acid per mol of the high molecular weight acid, which is a soap forming acid.

The present invention is based on the discovery that moderate molecular weight carboxylic acids, which are without the range of conventional soap-forming acids, can be used instead of the high molecular weight carboxylic fatty acids of the prior art, in the preparation of new kinds of complex compounds with salts of low molecular weight acids. It has also been found that if the moderate molecular weight carboxylic acids are utilized, a mol ratio as low as about 2 to 1 of low to moderate molecular weight acids can be effectively employed to prepare the novel complex compounds of this invention. More specifically, these complex compounds are prepared from at least one metal salt of low molecular weight carboxylic acid containing from about 1 to 3 carbon atoms and at least one metal salt of moderate molecular weight carboxylic acid containing from about 7 to 10 carbon atoms. For purposes of this invention, the aliphatic monocarboxylic acids containing from about 7 to 10 carbon atoms, and which are intermediate inchain length and in molecular weight when compared to the low molecular weight and high molecular weight carboxylic acids, are hereinafter designated as the intermediate molecular weight carboxylic acids.

The exact nature of the complex compounds of the invention is not fully understood. It is almost certain that they are not ordinary chemical compounds; but they may be a sort of Werner complex with coordinated valences. X-ray diffraction spectra obtained from various salt complexes in accordance with the invention, i.e. containing at least 2 moles of low molecular weight carboxylic acid for each mol of intermediate molecular weight carboxylic acid, show a pattern definitely inconsistent with that of a physical mixture of the low molecular weight carboxylic acid salt and the intermediate molecular weight carboxylic acid salt. The X-ray diffraction patterns of complexes composed of the same low molecular weight acid and intermediate molecular weight acid salts, but differing in the mol ratio of low to intermediate molecular weight acids employed, show differences indicating the existence of difi'erent chemical compounds rather than varying physical mixtures of the same chemical compounds. The temperatures at which the mixture of low and intermediate molecular weight carboxylic acid salts are heated or reacted together are also shown to be important by X-ray diffraction spectra. Patterns obtained from the products resulting from heating the mixture of salts at a temperature within the range of about 400 to 550 F. and at a temperature within the range of about 220 to 350 F. differ from each other indicating the existence of different chemical compounds. The preformed salt complexes of this invention are prepared at the higher temperatures, and hereinafterthe term salt complex will pertain to the product or products obtained by heating or reacting together the mixture of low and intermediate molecular weight carboxylic acid salts at a temperature of at least about 400 F.

In accordance with the present invention, complex.

compounds containing at least one metal salt of a low molecular weight carboxylic acid and at least one metal salt of an intermediate molecular weight carboxylic acid, in which the mol ratio of low to intermediate molecular weight acid is about 2:1 to 25:1, preferably about 4:1 to 12:1, may be incorporated into a Wide variety of liquid and semi-liquid materials of natural or synthetic origin to improve the utility of these materials. In one particular embodiment, these complex compounds of high metal content are incorporated in mineral and/or synthetic lubricating oils in grease-making proportions of about 5 to 30 wt. percent to produce greases having excellent load-carrying properties and high temperature stability characteristics. The complex compounds of the invention may also be employed in relatively small proportions, eg about 2 to 4 wt. percent as dispersants and corrosion inhibiting additives in residual fuels; as detergent additives in mineral or synthetic automotive lubricants; as extreme pressure and metal bonding additives in metal-working or cutting fluids and in gear lubriccants. By means of these complexes it is unexpectedly possible to disperse stably in oily media salts which separately have little or no solubility in oil and also thus to incorporate in the oily or non-aqueous organic media ex-z ceptionally high concentrations of the constituent metal, which may be the effective load-carrying agent.

The low molecular Weight acids contemplated in this invention include saturated carboxylic or fatty acids having from about 1 to 3 carbon atoms. These acids include formic, acetic, propionic and lactic acids. Acetic acid is particularly preferred for the purpose of this invention. In general, the low molecular weight carboxylic acid employed should have a saponification value of above about 600 and preferably about 900. Mixed low molecular Weight carboxylic acids wherein the acids contain from about 1 to 3 carbon atoms, and wherein the mixture of acids has an average saponification value of above about 540 may also be employed. I

The intermediate molecular Weight acids are those allphatic mo'nocarboxylic acids containing from about 7 to carbon atoms, preferably about 8 to 9 carbon atoms. Either saturated or unsaturated fatty acids may be utilized, though the saturated fatty acids are preferred. Straight chain acids are preferred, since they have a greater thickening power per given amount of material than the corresponding branched chain acids. This, in tprn, results in a lesser amount of acid required for a given hardness (in the case of greases) or given viscosity in the case of fluids or semi-fluids. Single or mixed intermediate molecular weight carboxylic acids having an average saponification value of from about 310 to 440, especially about 320 to 420, are preferred. Some of the intermediate molecular Weight monocarboxylic acids coming'within the above prescriptions are exemplified by:

Heptanoic (enanthic) Octanoic (caprylic) Nonanoic (pelargonic) Decanoic (capric) Commercial C7 to C 10 intermediate molecular weight acids containing minor amounts of acid having less than 7 or more than 10 carbon atoms can also be used, provided their average chain length is about 7 to 10. Thus, a commercial acid such as Wecoline AAC acid which has about 46 wt. percent capric, about 28 Wt. percent caprylic and about 26 Wt. lauric acid, is considered as an intermediate molecular acid within the definition of the invention as it averages about 170 mol. wt. and can be considered as a commercial capric (C acid.

The alkaline earth metals, calcium, strontium, magnesium and barium are used as the metal component of the complex. These metals afford greatest advantages when used as thickeners in the manufacture of greases, since they permit the production of greases having outstanding load-carrying characteristics and satisfactory structural stability at high temperatures and under mechanical stress even without the use of conventional extreme pressure and stabilizing agents. Calcium is particularly preferred in this respect. The alkaline earth metals differ in this respect from the alkali metals, i.e. sodium, potassium and lithium which are unsuitable for forming stable, grease systems.

The salt complexes of the invention may be prepared by coneutralization of a mixture of the acids with suitable bases, particularly the hydroxides and/or carbonates of the metals desired. The coneutralization step may be carried out in situ in the liquid menstruum to which the complex compound is to be applied in actual use, if the menstruum is stable under the conditions of neutralization. For example, the mixed acids may be coneutralized in a portion or all of the lubricating oil forming the dispersant of a grease to be thickened by the complex. Normally, the coneutralized material is heated to high temperatures of above about 400 F., preferably 430 to 510 F., prior to use in order to dehydrate the product and to promote the formation of the complex.

The coneutralization method is not necessary as long as both salts are present when heating to complexing temperatures. Thus, the complexes of the invention may also be prepared by separately preforming at least a portion or all of the low molecular weight carboxylic acid salt and/ or the intermediate molecular weight carboxylic acid salt, intimately mixing the salts, and then heating under substantially complex forming conditions. This method is especially useful when different alkaline earth metals are employed as bases for the salt constituents.

The use of preformed metal salts may also be desirable for other considerations. The production of salt complexes of the type here involved for the manufacture of greases, etc. required large amounts of low molecular weight carboxylic acids, such as glacial acetic acid. Since these acids are available in large quantities they may be purchased in carload or tank car lots, requiring plant tankage with piping to the kettles and precautions to prevent freezing. Other handling precautions are necessary due to the corrosive nature of these acids. By substituting preformed metal salts of the low molecular Weight acids employed in the preparation of the complexes, a large number of the drawbacks just mentioned may be eliminated. In addition, the preformed salts, particularly calcium acetate, in suitable purity are often cheaper than those formed in situ by reacting the metal base with the free acid. These advantages may be obtained by replacing about 30 to Wt. percent, preferably at least about 50 wt. percent, of the free acid with the preformed metal salt in formulating the complex compounds.

In general, the lubricating oil should have a viscosity Within the range of about 60 to 2500 SUS at F. and 35 to 200 SUS at 210 F., a pour point of about +20 to 75 E, and flash point of about 350 to 650 F. A viscosity index of 100 or higher is also desirable, though oils having a viscosity index below about 60 give better yield, i.e. grease with less penetration for a given content of thickener. As mentioned above, synthetic as well as mineral lubricating oils can be employed as part or all of the liquid phase of the grease, and they include synthetic lubricating oils of the hydrocarbon, hydrocarbon polymer, ester, complex ester, formal, mercaptal, polyalkylene oxide, silicone or similar types. Synthetic oils such as the diesters of aliphatic dicarboxylic acids like di-Z-ethylhexyl sebacate, di-C -Oxo azelate, diisooctyl azelate, and (ll-C -OXO-hCllPZt'tfi may be used. Other suitable synthetic oils are complex esters prepared from polybasic' carboxylic acids, polyhydric alcohols, monobasic acids and/or monohydric alcohols, such as the glycolcentered or dibasic acid centered complex esters.

Complex salt proportions of about 2 to 50 wt. percent, preferably about 10 to 30 wt. percent, based on the total weight of the grease, may be used in preparingthe improved greases of the invention. The resulting grease compositions are preferably homogenized in a Morehouse mill or Gaulin homogenizer at room temperatures or temperatures in the range of about to 200 F.

The complex can also be prepared in a low viscosity mineral lubricating oil and then the resulting mixture can be blended with a higher viscosity mineral lubricating oil to produce grease compositions Within the scope 0 this invention.

The detergency and extreme pressure characteristics of the complex compounds of the present invention may be incorporated in lubricating oils for purposes other than the preparation of greases. In this case also it is desirable to introduce relatively large proportions of active metal into the oil Without sedimentation problems. Both min eral and synthetic lubricating oils may be used. High metal content salt complexes of the alkaline earth metals, particularly magnesium, calcium and barium, have excellent detergent properties and will appreciably increase the extreme pressure characteristics of lubricating oils.

The same salt complexes may be added to metal working lubricants, such as cutting oils, drawing compounds, forging compounds, etc. of the mineral oil or emulsion type to ensure their extreme pressure characteristics. In

this case, the high metal complex compounds may replace.

or supplement additives containing such conventional load-carrying components as sulfur, chlorine, sulfur-chlorides, and phosphorus.

As previously mentioned, the temperature at which the mixture of salts of this invention is heated has a definite effect on the properties of the resulting products. For example, when these salts are prepared in grease-making proportions in a lubricating oil by coneutralization at a temperature below dehydration temperatures, for example, at the temperature attained by the evolution of heat of reaction, i.e. about 130 F., and below about 210 to 220 F., the resulting products have grease-like consistency and find use in special application. They 6 was cooled to about 250 F. Phenyl-alpha-naphthylamine was then added and dispersed in the mixture by stirring. Cooling was continued to a temperature of about 200 F. When this temperature was reached, the grease composition was passed through a Gaulin homogenizer and filtered.

The grease compositions prepared in accordance with the method outlined above were submitted to standard grease inspections such as ASTM penetration, dropping point, lubrication life, solubility in boiling water, Norma- Hoifman Oxidation Test, Timken Test, Almen Test, etc. The composition of these greases and their properties are tabulated below in Table I.

Table I Gr e 1 2 3 4 5 Formulation (Wt. percent):

Glacial acetic acid 5.0 8. 5 12.0 15.0 21. Caprylic acid 12.0 10.0 6.0 3.6 3. 0 Hydrated lime 7. 0 8. 9. 8 l1. 1 15.2 Phenyl alpha naphthylamine 0. 5 0. 5 0. 5 0. 5 0. 5 Mineral Lubricating Oil (55 SUB/210 F.) 69. 8 72. 5 71. 7 69. 8 60. 3 M01 ratio: Low molecular weight acid to intermediate acid 1:1 2:1 4. 8:1 10: 1 :1 Saponification N0. (Ex acetic) 389 389 389 389 389 Percent Ca. Metal (combined in complex) 3. 8 4. 6 5. 3 6. 0 8. 2 Properties:

Appearance Excellent, smooth, uniform ASTM Penetration (mm./l077 F.):

Unworkcd 220 176 262 340 355 Worked 60 strokes 278 160 293 355 385 Worked 100,000 strokes 315 245 350 400 Semifluid Dropping Point F.) ASTM D 500+ 500+ 500+ 500+ 500+ Wheel Bearing Test (660 r.p.m.) Pass Pass Pass Pass Pass N.L. G.I. Lubricating Life (hou (250 F., 10,000 r.p.m.) 846 2,100 651 Solubility in Boiling Water None None None None None Norma-Hoffman Oxidation Test (hours to 5 lb. pressure drop) 300 to 400. Storage Stability (113 days storage) Crust Formation None None None None None E.P. Properties:

Timken Test lbs. Load) Fail Fail Pass Pass Pass Almen Test:

15 wts. Shock Loading Fail Pass Pass Pass Pass 15 wts. Gradual Loading Pass Pass Pass Pass are, however, generally unsuitable for high temperature lubricating service. If the acids are coneutralized at dehydration temperatures, but at temperatures below which the complex formation or interaction is completed, i.e. from about 220 to 400 F., the resulting products are liquid or semi-fluid. On the other hand, when the preparation or heating of the mixture of salts in the lubricating oil is carried out at temperatures above about 400 F., and preferably from about 430 to 550 F., products with entirely different characteristics are formed that have grease-like consistency, high melting points, stability, ex cellent Almen Test results under shock or gradual loading conditions, etc. The maximum temperature is that at which thermal decomposition begins. Thermal decomposition of lubricating oil occurs above about 650 F.

The invention will be more fully understood by reference to the following specific examples illustrating various modifications of the invention:

EXAMPLE I A number of mineral oil base lubricating greases thickened with calcium salt complexes of acetic acid and caprylic acid and having the formulations given in Table 1 below were prepared as follows:

The hydrated lime and all of the mineral lubricating oil were charged to a fire-heated grease kettle. After intimately mixing the lime and oil to a smooth slurry with no external heating, the mixture of acetic acid and caprylic acid was charged to the kettle. After about 30 minutes, at which time heat of reaction had started to subside, the temperature was raised with stirring to about 480 F. At this temperature, heating was discontinued and stirring was continued while the mixture It will be seen that complexes containing at least about 2 moles of acetic acid per mol of caprylic acid yielded greases (Nos. 2 to 5) of excellent consistency, dropping point, outstanding load-carrying capacity, etc. Grease No. 1, containing an equimolar ratio of acetic to caprylic acid was far inferior with respect to extreme pressure characteristics at otherwise comparable conditions. Greases containing at least about 4.8 moles of acetic acid per mol of caprylic acid (Nos. 3 to 5) had particularly outstanding extreme pressure characteristics in that they passed both the shock and gradual loading Almen Test as well as the Timken Test at 45 lbs. load, the latter test being a requirement for acceptability of a grease for use in steel mills and particularly for use in Timken bearmgs.

EXAMPLE II A number of mineral oil base lubricating greases (Nos. A through E) having the formulations listed in Table II below were prepared substantially as described in Examplel.

Greases C and D were made according to the preferred embodiment of the present invention and Greases A and E were made for comparison.

Grease No. F for purposes of comparison was pre pared by charging hydrogenated castor oil, the Hydrofol Acid, the hydrated lime and all of the mineral lubricating oil to a fire-heated kettle equipped with agitating means. The mixture was heated to about F., and the acetic acid added. Heating was continued to a temperature of 500 F., heating was then discontinued and the grease was cooled to 200 F., while stirring. Thereafter, the grease was homogenized at a high rate of shear in a Gaulin homogenizer.

mineral lubricating oil.

'3 The composition and properties of the greases of this example are tabulated below in Table II.

blend. For example, a blend of about equal parts of these two types of greases results in a lubrication life, in a Table II Grew es A B C D E F Formulations (Wt. percent):

Glacial acetic acid 12.0 12.0 Oaprie acid, C10. Stearie acid, 01 Oaprylie acid. Cs 4. 5 Caproie acid 6.0 1.5 Hydrated limo- 10. 3 9. 8 Phenyl-alpha-n 0. 5 0. 5 Mineral Lubricating Oil (55 SUS 71. 2 71. 7 Mol Ratio: Acetic acid to higher acids- 3. 8 4. 5 Saponification No. of acids (Ex acetic) 1'83 413 Properties:

Appearance. Semi-fluid Excellent Excellent Excellent Excellent Excellent Dropping Point (F) 500+ 500+ 500+ 500+ 500 Penetrations (77 F. nun/l0):

Unworked 1 Poor 262 202 300 242 103 Worked 60 strokes. J Sturcture 280 293 325 232 144 Worked 100,000 strokes 370 350 372 340 E.P. Properites, Timken Test (40 lbs. load) Pass Pass Pass Pass Fail Fail *Grease F is listed for purposes of comparison. It was made with soa mercial stearic acid in the form of Hydroiol Acid 51 (hydrogenated fi It will be noted that these complex compounds contain in addition to the acetic acid an intermediate molecular weight acid or mixture of acids. The average saponification values of the acids, other than the acetic acid, are within the range of about 320 to 420, yielded greases (Nos. B through D) having excellent extreme pressure, thickening and stability characteristics. C and D were best in showing the least change in penetration upon being worked. A combination of acetic acid and stearic acid (Grease No. E) in high mol ratios gave a fairly high metal content greases with long lubrication life, but

p mixture from hydrogenated castor oil, 3.75%, and comsh oil acid), 3.75%.

bearing operating at 10,000 r.p.m. and 250 F., of about 5000 hours.

EXAMPLE III A number of mineral oil base lubricating greases thickened with calcium salt complexes of acetic acid and a commercial mixture of caprylic acid having the formulations listed in Table III below were prepared substantially according to the method described in Example I. The composition and properties of these greases are set forth in Table III below.

Table III Grease No Formulation (Wt. percent):

Glacial acetic acid Commercial Caprylic Acid Hydrated limo Phenyl-alpha-naphthylamine Mineral lubricating oil:

500 SUS/l00 F 900 SUS/100 F 5,000 SUS/l00 F Mol ratio: Acetic acid to higher aeids-.

Saponification No. (Ex acetic) Properties:

Appearanc Dropping Point F.) .Q.

Penetration (77 F. mn1./10):

Unwcrked Worked strokes Worked 100,000 strokes E. P. Properties Timken Test (40 lb. load) -I Excellent Poor Excellent 500 Excellent 500 500 310 342 41 370 Pass, narrow sear.

384 Over 400 1 5.0% Oaprolc, Caprylic, 20% Capric.

2 Cut-back by diluting Grease H with additional oil and homogenizing. B Cut-back by diluting Grease K with additional oil and homogenizing.

poor extreme pressure characteristics. A combination of acetic acid and caproic acid with only 6 carbon atoms per molecule (Grease No. A) has good extreme pressure characteristics, but has little, if any, grease structure.

The salt complex thickened grease of the invention can also be employed to greatly decrease the water solubility and to enhance the lubricating properties of complex soda soap thickened greases. The latter are well known in the art and are prepared by saponifying rapeseed oil at temperatures of about 450 to 520 F. in the presence of a By blending or combining the complex soda soap grease with a complex calcium ace 'tate-caprylate grease of this invention, the unexpected results described above are obtained. In addition, the channeling properties of the soda soap grease can be modified The ratios of Table III show that in greases prepared with the salt complex thickeners of this invention excellent yields are obtained along with good structural stability to mechanical working when the soap is directly dis persed in mineral lubricating oils of not more than about 600 SUS viscosity at F. It is therefore preferred to use such oils where possible. Quite often, however, higher viscosity oils of about 700 to 5000 SUS at 100 F. are required in industrial lubrication, particularly Where heavy loads are encountered in roller bearing service. The dispersal of the salt complexes in these higher viscosity oils may result in lower yields as well as less struc' tural stability (Grease No. I). Increasing the salt complex content when employing the higher viscosity oils improves the penetrations, but this method may be less to almost any extent by adjusting the composition of the 75 economical (Grease K). If these high complex content are diluted, they form products of very soft consistency when compared to the lower viscosity oil products with equal complex content (Grease L). It will be noted from Table III that excellent yields and good structural stability can be obtained by preparing the grease in a lower viscosity mineral oil, and then blending this grease with higher viscosity mineral oil to give the desired viscosity in the finished grease composition (Grease J).

EXAMPLE IV (SYNTHETIC ESTER AS MENSTRUUM) A grease was prepared from the following ingredients.

Formulation:

Glacial acetic acid wt. percent 12.0 Commercial caprylic acid do 6.0 Hydrated lime do.... 9.8 Phenyl-alpha-naphthylamine do 1.0 Dii-sooctyl azelate do 71.2 Mol ratio of acetic to higher acids 5.7 Sap. No. (Ex acetic acid) 327 Preparation: Similar to that described in Example I. Properties:

Appearance Excellent. Dropping point F.) 500+. Penetration, 77 F., mm./10

Worked 60 strokes 280. Worked 100,000 strokes 342. Norma-Hoffman Oxidation Test (hours to p.s.i. drop) 500+. Water washing, per cent loss none. Lubrication Life, hours (250 F./10,000 rpm.) 1724. Shell 4 Ball Test,

E.P. value (mean Hertz load) 48.1

These data show that the salt complexes of the invention can be used to thicken synthetic lubricating oil to grease consistency. The resulting grease compositions are suitbale for service operations over a broad temperature range, i.e. about 60 to 300 F. or more, and excellent extreme pressure properties. Heretofore, lithium soap thickened diesters have been the only synthetic lubricants meeting certain government specifications for loW temperature service. Lithium soap is, however, often in short supply and is quite expensive. It has now been found that a complex calcium soap thickener comprising a salt complex of the calcium salts of acetic acid and commercial caprylic acid formed in situ in the diester gives greases meeting the requirements of the government specifications.

EXAMPLE V (SYNTHETIC SILICONE MENSTRUUM) The preparation of stable silicone polymer greases by conventional methods is difficult due to the insolubility or different dispersibility of the soap thickeners in the silicone fluid. It has now been found that by employing a complex high calcium acetate-caprylate thickener, the desired greases can be easily prepared, the resulting grease compositions have high dropping points and are capable of lubricating anti-friction bearings at elevated temperatures over relatively long periods of time. In addition, these greases have relatively good load-carrying capacity on steel to steel combinations as compared to the Prior art greases or to the silicone fluid itself.

Two greases having the formulations tabulated below were prepared by charging all of the silicone fiuid and hydrated lime to a fire-heated kettle, mixing the materials together, and warming the mixture to 135 F. The acetic and commercial intermediate molecular weight acids were then added, and the mixture heated to 510 F. with stirring. At this point, heating was discontinued, and the grease was cooled while mixing at 250 F. Phenyl-alpha-naphthylamine was added, the grease cooled to 200 F., and then passed through a Morehouse mill.

The composition and properties of the greases are set forth in Table IV below.

TABLE IV Grease No M N Formulation (Wt. percent):

Glacial acetic acid 12.0 12.0 C ommercial caprylic acid 6. 0 6. 0 Hydrated lime 10. 0 9. 8 Phenyl-alpha naphthylamme. 0. 5 1. 0 Silicone Fluid 0 1 71. 5 Silicone Polymer Oil 550 2 71. 2 Properties:

Appearance Excellent, smooth uniform grease. Penetrations (77 F. mm./10):

Unworked 300 285 Worked 60 strokes 310 310 Worked 100,000 strokes 325 335 Dropping Point F.) 500+ 500+ Water solubility (Boiling water Nil N i] Norma Hoffman Oxidation (Hours to 5 p.s.i. drop) 400+ 400+ Lubrication Life, Hrs. (350 F., 10,000

rpm.) 500 350 Almen El. Test (Steel pin-steel bushings) Wgts. carried, 6 Pass Pass 1 Dow OorningMethyl phenyl polysiloxanes, high ratio of phenyl to methyl grouping. 1,060 SSU at F. 2 Methyl silicone. 400 SSU at 100 F.

The outstanding extreme pressure properties of the greases prepared in accordance with the present invention should be noted. When attempts were made to prepare greases from the same Silicone Fluid 710 with either lithium soap or with a complex of calcium stearate and calcium acetate the products failed to carry 3 weights in the steel to steel Almen Test.

EXAMPLE VI As previously mentioned, xallcaline earth metals other than calcium can be employed as the metal constituent of the salt complex compounds of this invention. This embodiment is exemplified by the use of barium or mixed barium-calcium salt complexes to impart to the final grease composition excellent lubricating properties, particularly outstanding extreme pressure characteristics.

The saponification of the combined low and intermediate molecular weight acids with barium hydroxide, particularly barium octahydrate, requires large amounts of the base. It has been found that the requirement of barium octahydnate can be materially reduced by employing part of the low molecular weight acid as the preformed barium salt. Not more than 60%, preferably about 30 to 50%, of the low molecular weight acid can be employed, however, as the preformed barium salt; the remaining acid must be neutralized in situ; This embodiment is further described in the following grease preparations.

Grease No. 6, having the formulation tabulated in Table V, was prepared by charging all of the mineral oil and the barium acetate to a fire-heated kettle. The materials were mixed and barium hydroxide, dissolved in boiling water, was added. The acetic and commercial caprylic acid were then blended into the mixture, which was then heated with stirring until all of the water was removed. The mixture was heated rapidly to 510 F., and was then cooled to 275 F. While stirring. Phenylalpha-naphthylamine anti-oxidant was added, and the mixture further cooled to 200 F. The grease product was then homogenized by passage through a Gaulin homogenizer at 6000 p.s.i.

Grease No. 7, having the formulation tabulated below, was prepared substantially the same as Grease No. 6, except that approximately 50% of the low molecular weight acid was employed as the preformed barium acetate, in the form of dry crystals, in place of the Bia( OH 8H O solution.

Grease No. 8, having the formulation tabulated below,

It i was prepared substantially the same as Grease No. 6, except that hydnated lime was substituted for the barium hydroxide.

TABLE V Criticality of Temperature Following the general procedure of Example I, a series of products were prepared for the purpose of il- Grease No 6 Formulations (Wt. percent): Glacial acetic acid. Barium acetate- Caprylic acid, commercial grade. BE(OH)TSHZO Hydrated lime-.

Phenyl-alpha-naphthylamine Mineral lubricating oil (55 SUS/210 F.)

Mol Ratio: Acetic acid to Caprylic, commercial grade. Saponification N 0. (Ex acetic) Properties:

Appearance Excellent, stable dispersion but quite fluid.

Dropping Point F.)

Penetration (77 F. nun/10):

Unworked. Worked 60 strokes Worked 100,000 strokes.

Timken Test lbs. load) i 'an -1 Excellent smooth uni- Excellent smooth solid form soft grease. grease structure.

Pass, narrow scar Pass, narrow Scar.

1 9.22% additional mineral lubricating oil was added to replace water of hydration in Ba hydrate.

EXAMPLE VII Another important advantage resulting from the use of an intermediate molecular Weight acid in conjunction with a low molecular Weight acid to form the salt complex grease thickener is that it appears to prevent hardening and crust formation in the final grease composition. This feature of the present invention is shown by the data intable VI.

Grease 0, having the formulation shown in Table VI, was prepared in the same way as in Example I.

Grease P, having the formulation shown in Table VI, was prepared similarly to Grease 0 except that Hydrofol Acid 51, a commercial stearic acid, was employed in place of the intermediate molecular weight acid, caprylic acid.

TABLE VI lustrating the effect of temperature upon the compositions.

EXAMPLE VIII Dropping Point F.) Penetrations (77 F.1nn1./10):

Unworked Worked strokes smooth grease.

Worked 100,000 strokes Penetration after 10 days storage (worked 60 strokes). Crust formation Mol ratio: Acetic to higher acids. Sap. No. of acids (Ex acetic).... Timken Test (40 lbs. load) Scar N(()ii;ma)-Hoilman Oxidation Test (hours to 5 p.s.i.

Lubrication Life (hours) (10,000 r.p.m., 250 F.)--.. Condition of grease after 6 mos 2,100 Unchanged Surface hardening (crust) gradually spread through grease until it became very hard, mm./l0 penetration.

EFFECT OF METAL COMPONENT OF THE MIXED SALT COMPLEX EXAMPLE IX Compositions d, e, and f.A series of compositions were prepared using the same amount of acids and a sufiioient amount of metal base to form substantially a Table VII Composition a. b. c.

Formulation (wt. percent):

Glacial Acetic Acid..-- 12.0. 12.0. 12.0.

Wecoline AAC 6.0- 6.0- 6.0.

Hydrated lime 10.0-..-- 10.0. 10.0.

Phcnyl wnapthylamine 1.0 1.0 1.0.

Min(e)ra}lT Lubricating Oil, 55 SUS at 71.0- 71.0. 71.0.

Max. Temp. of mfg No external heating 320 F 450 F Properties:

Appearance Fxeollent Semi-Solid non- Excellent.

homogeneous.

Dropping Point, F 500 F. 500 F.

ASTM Penetration mm./1O 77 F.:

Unworkcd.. 289 Poor structural 275.

stability.

Worked strokes. 295. Timken Test lbs. carried 45+. Almen Test Wgts. carried:

Gradual Loading 15.

Shock L din l 15.

Water Solubility Insoluble Insoluble Insoluble. Lubrication Life Good. Excellent.

1 The grease boiled and expanded during the dropping point test due to formation of steam during heating, although the grease did not actually melt until it reached 500 F 2 Wecoline AAC acid is a mixture of about 28 wt. percent caprylic; about 46 wt. percent capric and about 26 percent lauric acids.

3 ABEC-NLGI Spindle Test.

As seen by Table VII, when no external heating is applied as in Composition a, a grease is formed having good load-carrying and extreme pressure properties, but which cannot be satisfactorily used for high temperature operation because of the water of reaction present in the composition. Thus, it is to be noted that in obtaining the neutral composition. Each composition was prepared in the same manner as Composition 0 of Example VIII except that .difiercnt metal bases were used in place of the lime. The compositions prepared and their properties are summarized in Table VIII which follows along with Composition 0 for comparison.

Table VIII Composition d. e f c.

Formulation (Wt. percent):

Glacial Acetic Acid- 12.0- 12.0. 12.0.

Wecoliue AAC- 6.0.-.. 6.0.. 6.0.

Ba(OH)i 23.1

NaOH

LiOH.H2O 10.0-

Hydrated Lime -0. 10.0.

Phenyla-naphthylamine- 1.0. 1.0- 1.0.

Mineral Lubricating Oil, 55 SUS at 210 F 57.9- 71.0. 71.0. 71.0. Properties: y

Appearance Fluid homogeneous--. Fluid homogeneous Fluid homogeneous. Excellent.

Penetration 77 F. mm./-Unworked Sc ll-Fluid. Semi-Fluid. 275.

Worked 60 strokes.. Flllld, ulti. 295.

'limken Test lbs. carried passes, fails 20 Falls 20 Fails dnopping point of Composition a, that the grease boiled and expanded due to the formation of steam. On the other hand, when the grease is dehydrated at temperature of 320 F. as represented 'by Composition b, a semi-solid, non-homogeneous material resulted having poor structural stability. When the same composition was prepared at temperature of 450 F., as represented by Composition c, a firm solid grease structure resulted as opposed to the semi-solid structure of Composition b. Thus, Table VII clearly demonstrates the critioa lity of preparing the compositions of the invention at relatively high temperatures, i.e. in excess of 400 F., in order to obtain a dehydrated grease in which the maximum thickening effect of the salts is obtained.

Table VIII shows that when barium hydroxide is used that a lubricant is obtained having fairly good properties in the Timken test but which is fluid as compared to a similar composition in which hydrated lime is used to form the metal component. This is demonstrated by comparisons of Compositions d and 0, both of which contain the same amount of acid to which sufficient metal base was added to form a substantially neutral composition. When alkali metals are used, as demonstrated by Compositions e and f, not only is a fluid composition obtained, but the extreme pressure properties as measured by the Timken test are much lower than when an alkaline earth metal is used. Although 10 wt. percent of metal base was used in each of Compositions e,

1.55 f, and c, in each case the molar amount of metal was about the same and neutral compositions were obtained due to the variation in the molecular Weights of the hydroxides so that all compositions of Table VIII represent fair comparisons.

EFFECT OF BRANCHED INTERMEDIATE MOLECULAR ACID As COMPARED To STRAIGHT CHAIN INTERMEDIATE Mo- LECULAR WEIGHT ACID EXAMPLE X Compositions g and h.--Cmpositions g and h were made following the general procedure of preparing Composition 0, except that 2 ethylhexoic acid was used in place of the Wecoline AAC acid.

EFFECT OF USING SILICONE OIL EXAMPLE XI ular Weight was added to a slurry of gms. of hydrated lime in 925 gms. of naphthenic lubricating oil of 600 SUS viscosity at 100 F. and stirred in a Hobart mixer. The mixture was heated to 350 F. and held at this temperature for one hour. Then a sample of 100 gms. was withdrawn for tests. The remainder of the grease in the mixer was heated to 430 F. and held at this temperature for one hour, after which it was withdrawn for testing too.

Tests were made for X-ray diffraction patterns with a Norelco Diflractometer, using CuK alpha radiation, lambda 1.542 and nickel filter. The principal D-spacings, in Angstrom units, in the X-ray diffraction patterns of the two samples prepared at different temperatures were as follows.

For the sample prepared at 350 F.: 28.0, 16.7, 11.7,

8.6, 7.5 For the sample prepared at 430 F.: 15.5, 9.6, 9.2, 3.47

These measurements show definitely that the grease made at 430 F. was a dilierent composition from that made at 350 F.

What is claimed is:

1. A lubricating grease composition comprising a major proportion of a lubricating oil selected from the group consisting of mineral lubricating oil and synthetic lubri- Table IX Composition Formulation (wt. percent):

Glacial Acetic Acid 12.0 12.0 12.0 12.0. Wecoline AAC fl 0 6.0. 2-Ethylhexoic Acid 6.0. 6.0 Hydrated lime 10.0. 10.0. 10.0. LiOH'H20 10.0. Phenyla-naphthylamine 1.0 1.0- 1.0- 1.0. Mineral Lubricating Oil SUS at 210 F 71.0 71.0 71.0 Silicone Oil 71.0. Properties:

Appearance Excellent Grainy- Unhomo- Excellent.

' geneous grainy. Dropping Point 1? 500+ 500+. ASIM Penetrations mm./l0 77 F.:

Unworked 275 Semi-Fluid- Senn-Fmd 300. Worked 60 Strokes. 29 Fluid 310. Timken Test lbs. carried 45+ Almen Test:

Gradual Loading. 1% 15 6. Shock Loading 15 15. Water Solubility boiling water. Insoluble Insoluble. Lubrication Lite 1 Too soft Good.

1 ABEC-NL GI Spindle Test. 2 Semi-fluid-does not form a stable grease structure.

Comparisons between Compositions c and g illustrate that a much softer composition is obtained using a branched chain acid as represented by the 2-ethylhexoic acid of Composition g, as compared to the harder solid grease composition obtained from the straight chain acids of Composition 0. While the acids of Composition 0 averaged C and the Z-ethylhexoic acid of Composition g is a C acid, a general effect of shortening the acid chain is to increase hardness, and yet the opposite result was obtained when the shorter chain acid was branched. Comparisons of Compositions g and It show that a less satisfactory lubricant resulted by use of lithium. Composition i shows a grease having good properties except that its load-carrying ability is less than a corresponding grease prepared with mineral oil as represented by Composition c.

EXAMPLE XII A mixture of gms. of acetic acid and 75 gms. of straight-chain, saturated fatty acid of average moleceating oil, and from 10 to 50 wt. percent of dehydrated complex of at least one calcium salt of low molecular weight saturated monocarboxylic acid having in the range of l to 3 carbon atoms per molecule,'and at least one calcium salt of intermediate molecular weight straight chain monocarboxylic acid having in the range of 7 to 10 carbon atoms per molecule, the molar ratio of low to intermediate molecular weight carboxylic acid being in the range of 4:1 to 12: 1, and said complex being formed at a temperature in the range of 400 to 500 F.

2. A lubricating grease composition which comprises a major proportion of a lubricating oil selected from the group consisting of mineral lubricating oil and synthetic lubricating oil and about 10 to 30 wt. percent of a dehydrated complex of at least one calcium salt of low molecular weight saturated monocarboxyli'c acidhaving in the range of l to 3 carbon atoms per molecule and having a saponification value in the range of 600 to 900, and at least one calcium salt of intermediate molecular weight St a g t chain monocarboxylic acid having in the range 17 of 7 to carbon atoms per molecule and having a saponification value in the range of 310 to 440, the molar ratio of low to intermediate molecular weight carboxylic acid being in the range of 4:1 to 12:1 and said complex being formed at a temperature in the range of 400 to 550 F.

3. The grease composition of claim 2 wherein said low molecular weight carboxylic acid is acetic acid.

4. The grease composition of claim 2 wherein said lubricating oil is a synthetic lubricating oil.

5. The grease composition of claim 2, wherein said lubricating oil is a mineral lubricating oil.

6. The method of preparing a dehydrated lubricating grease composition comprising dispersing in a major amount of lubricating oil selected from the group consisting of mineral lubricating oil and synthetic lubricating oil, calcium salt of a low molecular weight saturated monocar-boxylic acid having from 1 to 3 carbon atoms per molecule and a calcium salt of an intermediate molecular weight straight chain monocarboxylic acid having in the range of 7 to 10 carbon atoms per molecule, the molar ratio of low to intermediate molecular weight acid being in the range of 4:1 to 12: 1, and the amount of said calcium salts being in the range of 10 to 30 Wt. percent, based on finished product, heating the mixture to a tem- 18 perature in the range of 400 to 550 F., and cooling to obtain said grease composition.

7. The method of claim 6 wherein said lubricating oil has a viscosity in the range of to 2500 SUS at F., and is a mineral lubricating oil.

8. The method of claim 6 wherein said calcium salts are formed in situ in lubricating oil by neutralization of the corresponding acids with a calcium base.

9. The method of claim 6 wherein said calcium salt of the low molecular weight carboxylic acid is added as such to said lubricating oil before the admixture is heated.

10. The method of claim 6 wherein said lubricating oil comprises a relatively low viscosity mineral lubricating oil and a relatively high viscosity mineral lubricating oil, the low viscosity oil being the menstruum in which said complex thickener is prepared and said relatively high viscosity oil being added after said cooling to obtain the final desired calcium salt content.

References Cited in the file of this patent UNITED STATES PATENTS 2,417,432 McLennan Mar. 18, 1947 2,863,847 Morway Dec. 9, 1958 

1. A LUBRICATING GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A LUBRICATING OIL SELECTED FROM THE GROUP CONSISTING OF MINERAL LUBRICATING OIL AND SYNTHETIC LUBRICATING OIL, AND FROM 10 TO 50 WT. PERCENT OF DEHYDRATED COMPLEX OF AT LEAST ONE CALCIUM SALT OF LOW MOLECULAR WEIGHT SATURATED MONOCARBOXYLIC ACID HAVING IN THE RANGE OF 1 TO 3 CARBON ATOMS PER MOLECULE, AND AT LEAST ONE CALCIUM SALT OF INTERMEDIATE MOLECULAR WEIGHT STRAIGHT CHAIN MONOCARBOXYLIC ACID HAVING IN THE RANGE OF 7 TO 10 CARBON ATOMS PER MOLECULE, THE MOLAR RATIO OF LOW TO INTERMEDIATE MOLECULAR WEIGHT CARBOXYLIC ACID BEING IN THE RANGE OF 4:1 TO 12:1, AND SAID COMPLEX BEING FORMED AT A TEMPERATURE IN THE RANGE OF 400* TO 500*F. 